Active Skid Control System (ASC)
DTC C1000: Abnormality in stoplight switch circuit
CAUTION
^ If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
^ When the hydraulic unit (integrated with ASC-ECU) is replaced, always perform the calibration of steering wheel sensor, G and yaw rate sensor, brake fluid pressure sensor, cut valve, and inlet valve.
CIRCUIT OPERATION
ETACS-ECU sends the ON signal generated when the brake pedal is depressed and OFF signal generated when the pedal is released to ASC-ECU via CAN bus lines.
DTC SET CONDITIONS
This diagnostic trouble code is set in the following case.
^ The vehicle has run for a long time with the stoplight switch turned ON.
^ The OFF status of the stoplight switch does not match the vehicle behavior.
PROBABLE CAUSES
^ Improper adjustment of stoplight switch installation position
^ Malfunction of the stoplight switch
^ Malfunction of the stoplight
^ Damaged wiring harness and connectors
^ Malfunction of ETACS-ECU
^ Malfunction of the ASC-ECU
DIAGNOSIS
Required Special Tools:
^ MB991958 Scan Tool (M.U.T.-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827 M.U.T.-III USB Cable
^ MB991910 M.U.T.-III Main Harness
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. After repairing the CAN bus line, go to Step 2.
STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C1000 set?
YES: Go to Step 3.
NO: This diagnosis is complete.
STEP 3. Battery check
Q: Is the battery in good condition?
YES: Go to Step 4.
NO: Charge or replace the battery, and the go to Step 16.
STEP 4. Stoplight operation check
Check that the stoplight is turned "ON" when the brake pedal is depressed, and that the stoplight is turned "OFF" when the brake pedal is released.
OK:
When the brake pedal is released: OFF
When the brake pedal is depressed: ON
Q: Is the check result normal?
YES: Go to Step 17.
NO: Go to Step 5.
STEP 5. Check for stoplight switch installation
Q: Is the check result normal?
YES: Go to Step 6.
NO: Install the stoplight switch correctly. Then, go to Step 19.
STEP 6. Stoplight switch continuity check
1) Remove the stoplight switch.
2) Connect the circuit tester (range) to the stoplight switch connector terminal Nos. 1 and 2.
3) When continuity does not exist with the plunger pressed from the outer case end face by the dimension shown in the figure, and when continuity exists with the plunger released, the switch is in good condition.
Q: Is the check result normal?
YES: Go to Step 7.
NO: Replace the stoplight switch. Then go to Step 19.
STEP 7. Check for diagnostic trouble codes of other systems
Check that no DTC is set by the rear combination light.
Q: Is the check result normal?
YES: Go to Step 8.
NO: Check whether the combination meter-related DTC is set. Then go to Step 19.
STEP 8. ETACS-ECU fuse No.2 check
Q: Is the check result normal?
YES: Go to Step 14.
NO: Go to Step 9.
STEP 9. Connector check: C-43 joint connector, C-47 intermediate connector, C-48 stoplight switch connector, C-304 ETACS-ECU connector, C-309 ETACS-ECU connector, C-312 ETACS-ECU connector, D-11 intermediate connector, D-17 intermediate connector, F-05 high-mounted stoplight, F-06 rear combination light (stoplight: RH), F-25 rear combination light (stoplight: LH), F-27 intermediate connector
Q: Is the check result normal?
YES: Go to Step 10.
NO: Repair the defective connector. Then, replace fuse No. 2.
STEP 10. Wiring harness check between C-48 stoplight switch connector and C-312 ETACS-ECU connector and C-43 joint connector
1) Disconnect C-43 joint connector, C-48 stoplight switch connector, and C-312 ETACS-ECU connector.
2) Check the continuity (short to ground) between C-48 stoplight switch connector terminal No. 1 and the ground.
OK: No continuity
Q: Is the check result normal?
YES: Go to Step 11.
NO: The short circuit may be present in the wiring harness between C-48 stoplight switch connector terminal No. 1 and C-43 joint connector terminal No. 2 or between C-48 stoplight switch connector terminal No. 1 and C-312 ETACS-ECU connector terminal No. 16. Repair the damaged wiring harness. Then, replace fuse No. 2.
STEP 11. Harness check between C-48 stoplight switch connector and C-304 ETACS-ECU connector
1) Disconnect C-48 stoplight switch connector and C-304 ETACS-ECU connector.
2) Check the continuity (short to ground) between C-48 stoplight switch connector terminal No. 2 and the ground.
OK: No continuity
Q: Is the check result normal?
YES: Go to Step 12.
NO: The short circuit may be present in the wiring harness between C-48 stoplight switch connector terminal No. 2 and C-304 ETACS-ECU connector terminal No. 1. Then, replace fuse No. 2.
STEP 12. Wiring harness check between C-43 joint connector and F-06 rear combination light (stoplight: RH) connector.
1) Disconnect C-43 joint connector and F-06 rear combination light (stoplight: RH) connector.
2) Check the continuity (short to ground) between C-43 joint connector terminal No. 1 and the ground.
OK: No continuity
Q: Is the check result normal?
YES: Go to Step 13.
NO: The short circuit may be present in the wiring harness between C-43 joint connector terminal No.1 and F-06 rear combination light (stoplight: RH) connector terminal No.4. Then, replace fuse No. 2.
STEP 13. Check the wiring harness between C-43 joint connector and F-25 rear combination light (stoplight: LH) connector, and between C-43 joint connector and F-05 high mounted stoplight connector.
1) Disconnect C-43 joint connector, F-05 high-mounted stoplight connector and F-25 rear combination light (stoplight: LH) connector.
2) Check the continuity (short to ground) between C-43 joint connector terminal No. 12 and the ground.
OK: No continuity
Q: Is the check result normal?
YES: Replace fuse No. 2.
NO: The short circuit may be present in the wiring harness between C-43 joint connector terminal No. 12 and F-05 high-mounted stoplight connector terminal No.1 or between C-43 joint connector terminal No.12 and F-05 rear combination light (stoplight: LH) connector terminal No.4. Repair the damaged wiring harness. Then, replace fuse No. 2.
STEP 14. Voltage measurement at C-304 ETACS-ECU connector
CAUTION
The measurement must be performed without the brake pedal depressed (not operated).
Measure the voltage between the terminal No. 1 and the body ground by backprobing.
OK: System voltage
Q: Is the check result normal?
YES: Go to Step 15.
NO: Replace the ETACS-ECU. Then, go to Step 19.
STEP 15. Voltage measurement at C-48 stoplight switch connector
1) Disconnect the connector, and measure at the wiring harness side.
2) Measure the voltage between the terminal No. 2 and the body ground.
OK: System voltage
Q: Is the check result normal?
YES: Go to Step 16.
NO: An open circuit may be present in the wiring harness between C-304 ETACS-ECU connector terminal No. 1 and C-48 stoplight switch connector terminal No. 2. Repair the wiring harness.
STEP 16. Voltage measurement at C-43 joint connector
CAUTION
The measurement must be performed with the brake pedal depressed.
1) Disconnect the connector, and measure at the wiring harness side.
2) Measure the voltage between the terminal No. 2 and the body ground.
OK: System voltage
Q: Is the check result normal?
YES: Go to Step 17.
NO: An open circuit may be present in the wiring harness between C-43 joint connector terminal No. 2 and C-48 stoplight switch connector terminal No. 1. Repair the wiring harness.
STEP 17. Voltage measurement at C-312 ETACS-ECU connector
1) Without disconnecting the connector, measure by backprobing.
2) Measure the voltage between the terminal No. 16 and the body ground.
OK:
The brake pedal is released: Approximately 0 V
The brake pedal is depressed: System voltage
Q: Is the check result normal?
YES: Go to Step 18.
NO: An open circuit may be present in the wiring harness between C-312 ETACS-ECU connector terminal No. 16 and C-48 stoplight switch connector terminal No. 1. Repair the wiring harness.
STEP 18. Check whether the DTC is reset.
Q: Is DTC 1000 set?
YES: Replace the hydraulic unit (incorporates in ASC-ECU). Then go to Step 19.
NO: Intermittent malfunction.
STEP 19. Check whether the DTC is reset.
Q: Is DTC 1000 set?
YES: Return to Step 1.
NO: The procedure is complete.